The most important problem of public safety is fire. As the degree of industrialization is increased and the extent of urbanization is enlarged, the hazard caused by fire is more severe. In industrially developed countries, the key point of fire extinguishing and prevention is tilted from “extinguishing” to “prevention”, and the requirements for flame retardancy are being put into effect in various materials in daily life. As is well known, at present, flame retardants used in our country are mainly conventional flame retardants. Although conventional inorganic flame retardants and halogen-based flame retardants have high efficiency of flame retardancy and wide range of applications, most of them have remarkably adverse effects on mechanical and physical properties of base materials. More importantly, most of halogen-containing flame-retardant materials have secondary hazards, such as large amount of smoke, emission of toxic or corrosive gases, etc., in combustion, and environment and human safety are severely threatened. The requirements for high-efficiency flame retardants have become more and more apparent in modern society. As compared to inorganic flame retardants and halogen-containing flame retardants, phosphorus-containing flame retardants have very remarkable advantages, such as low price, no toxicity, no metal, wide application range for base materials, and thus have become the decided trend of development in the industry of flame retardants. The phosphorus-nitrogen-based intumescent flame retardants are a type of flame retardant which has well developed in recent period. It is composed of three parts, which are an acid source (a dehydration agent), a gas source (a nitrogen-containing foaming agent), and a carbon source (a charring agent). Plastics, to which these flame retardants with phosphorus and nitrogen as main active elements are added, may generate a uniform and compact foam layer on the surface when heated. This foam layer insulates heat, blocks oxygen, and inhibits smoke. Furthermore, it may inhibit the melt drip phenomenon to some extent, and thus has significant flame-retardant effect. It is to be emphasized that the flame-retardant effect of the phosphorus-nitrogen-based intumescent flame retardant is greatly related with the added amount of the flame retardant, and a good flame-retardant effect may be obtained only if the added amount reaches a certain proportion. In addition, an optimal flame-retardant effect for a base material may be effectively obtained only if the phosphorus-nitrogen intumescent flame retardant matches with the type of high polymer.
Since fires cause great direct economic loss and subsequent long-term social loss, the prevention becomes more and more important and urgent. It is desirable to take preventive measures, such as flame retarding, in various aspects of social life. However, with respect to oily paints frequently used in the construction industry and daily life, there is still no flame retardant with good effect at present. This is because paints are organic polymer materials, which are difficult to be flame-retardant. The addition of conventional inorganic flame retardants and halogen-based flame retardants will cause deterioration in mechanical and physical properties of paints, such as loss of gloss, poor water resistance, easy generation of cracks, and reduction of adherence. Therefore, the flame retarding of paints has been always a great challenge in the field of flame retardants. To our knowledge, there are only several patented technologies related to the flame retarding of paints over the world. All of these flame retardants have a few common disadvantages, such as the influence on mechanical and physical properties of paints, containing halogen, high production cost, etc. As an example, the cyclic phosphate ester in European Patent EP 389,433 has high cost and complex process flow. Furthermore, it is only suitable for a few types of paints. As another example, in U.S. patent application US2010/132332A1, the flame retardant has good compatibility with resins, but it has complex production process and relatively high cost. It is mainly used in the flame retarding of plastic and rubber products, and has a certain limit for the application range of resins. Romanian Patent Rom.RO 94,457 has disclosed a formulation of a flame-retardant paint, which uses non-flammable phthalate linseed oil as a base material, with ammonium hydrogen phosphate hydrate and sodium carbonate added as flame retardants. This is a fireproof linseed oil coating, rather than a fireproof paint with corrosion-resistant and protective effects in conventional sense. Ammonium hydrogen phosphate and sodium carbonate are inorganic salts, which have poor compatibility with paints, are prone to absorb moisture, and will change mechanical and physical properties of most resins. Chinese patent application CN101629043A discloses a fireproof flame-retardant paint. However, this paint is only used as the flame-retardant on ferrous metal surfaces, and phosphorus oxychloride, which is a highly toxic and highly corrosive compound, is involved in the production process. U.S. Pat. No. 6,686,403 discloses a formulation of flame-retardant paint, formed by using melamine, pentaerythritol, and melamine phosphate in a certain ratio, as raw materials of acid source and carbon source, and stirring and mixing uniformly with a paint component, and the flame-retardant effect may be obtained only if a paint baking process is carried out. Therefore, this technology does not solve the problem to allow for wide-range flame retarding of various paints, either. The flame retardant of the present disclosure is different from the inventions which have been reported and has inventiveness.